The mobile search market grew by 38% in Europe year on year in June, while gains in the US market were more impressive, with the number of people searching via mobile rising by 68% compared with June 2007’s figures.

The figures, released by online measurement firm comScore, revealed that 4.5m Europeans and 20.8m US mobile users used mobile search in June.

The growth in the use of mobile search has been driven by a number of factors, including the growing availability and use of smartphones such as the iPhone, and the introduction of more attractive data plans by mobile phone networks.

The highest penetration rates for mobile search were in the UK, at 9.5%, with the US following closely behind at 9.2%.

Unsurprisingly, Google is the leading search engine for mobile internet users, taking 63% of the market in the US, and 74% in the UK. In Spain, Germany and Italy it is even more dominant. Yahoo ranks second in all of these markets, with 34.6% of mobile search in the US, and 16.2% in the UK.

According to comScore analyst Alistair Hill: “It is interesting to note that as we see the number of mobile search users increase, the frequency of activity is also growing. Meanwhile, the number of U.S. users accessing mobile search has more than doubled as a result of expanded 3G penetration and smartphone adoption, as well as the proliferation of flat-rate data plans. We have also seen a substantial improvement to the mobile search offerings in the U.S. market.”